Indicates if sidebar is in the flat mode.

<div class="definition">
    Boolean, default = false
</div>

If sidebar is in the flat more, only node icon will be displayed. Parent child structures are also ignored. Flat mode is
useful to make sidebar take less space.
<div style="height: 10px"></div>

You can define it during object creation:

<textarea class="javascript">
let sidebar = new w2sidebar({
    name : 'sidebar',
    flat : true,
    nodes: [
        { id: 'id-1', text: 'Level 1' },
        { id: 'id-2', text: 'Level 2' },
        { id: 'id-3', text: 'Level 3' }
    ]
});
</textarea>

or during run-time:

<textarea class="javascript">
w2ui.sidebar.flat = true;
w2ui.sidebar.refresh();
</textarea>